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      1 /*
      2  * Copyright (C) 2008 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include <hardware_legacy/uevent.h>
     18 
     19 #include <malloc.h>
     20 #include <string.h>
     21 #include <unistd.h>
     22 #include <poll.h>
     23 #include <pthread.h>
     24 
     25 #include <sys/socket.h>
     26 #include <sys/un.h>
     27 #include <sys/queue.h>
     28 #include <linux/netlink.h>
     29 
     30 
     31 LIST_HEAD(uevent_handler_head, uevent_handler) uevent_handler_list;
     32 pthread_mutex_t uevent_handler_list_lock = PTHREAD_MUTEX_INITIALIZER;
     33 
     34 struct uevent_handler {
     35     void (*handler)(void *data, const char *msg, int msg_len);
     36     void *handler_data;
     37     LIST_ENTRY(uevent_handler) list;
     38 };
     39 
     40 static int fd = -1;
     41 
     42 /* Returns 0 on failure, 1 on success */
     43 int uevent_init()
     44 {
     45     struct sockaddr_nl addr;
     46     int sz = 64*1024;
     47     int s;
     48 
     49     memset(&addr, 0, sizeof(addr));
     50     addr.nl_family = AF_NETLINK;
     51     addr.nl_pid = getpid();
     52     addr.nl_groups = 0xffffffff;
     53 
     54     s = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
     55     if(s < 0)
     56         return 0;
     57 
     58     setsockopt(s, SOL_SOCKET, SO_RCVBUFFORCE, &sz, sizeof(sz));
     59 
     60     if(bind(s, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
     61         close(s);
     62         return 0;
     63     }
     64 
     65     fd = s;
     66     return (fd > 0);
     67 }
     68 
     69 int uevent_get_fd()
     70 {
     71     return fd;
     72 }
     73 
     74 int uevent_next_event(char* buffer, int buffer_length)
     75 {
     76     while (1) {
     77         struct pollfd fds;
     78         int nr;
     79 
     80         fds.fd = fd;
     81         fds.events = POLLIN;
     82         fds.revents = 0;
     83         nr = poll(&fds, 1, -1);
     84 
     85         if(nr > 0 && (fds.revents & POLLIN)) {
     86             int count = recv(fd, buffer, buffer_length, 0);
     87             if (count > 0) {
     88                 struct uevent_handler *h;
     89                 pthread_mutex_lock(&uevent_handler_list_lock);
     90                 LIST_FOREACH(h, &uevent_handler_list, list)
     91                     h->handler(h->handler_data, buffer, buffer_length);
     92                 pthread_mutex_unlock(&uevent_handler_list_lock);
     93 
     94                 return count;
     95             }
     96         }
     97     }
     98 
     99     // won't get here
    100     return 0;
    101 }
    102 
    103 int uevent_add_native_handler(void (*handler)(void *data, const char *msg, int msg_len),
    104                              void *handler_data)
    105 {
    106     struct uevent_handler *h;
    107 
    108     h = malloc(sizeof(struct uevent_handler));
    109     if (h == NULL)
    110         return -1;
    111     h->handler = handler;
    112     h->handler_data = handler_data;
    113 
    114     pthread_mutex_lock(&uevent_handler_list_lock);
    115     LIST_INSERT_HEAD(&uevent_handler_list, h, list);
    116     pthread_mutex_unlock(&uevent_handler_list_lock);
    117 
    118     return 0;
    119 }
    120 
    121 int uevent_remove_native_handler(void (*handler)(void *data, const char *msg, int msg_len))
    122 {
    123     struct uevent_handler *h;
    124     int err = -1;
    125 
    126     pthread_mutex_lock(&uevent_handler_list_lock);
    127     LIST_FOREACH(h, &uevent_handler_list, list) {
    128         if (h->handler == handler) {
    129             LIST_REMOVE(h, list);
    130             err = 0;
    131             break;
    132        }
    133     }
    134     pthread_mutex_unlock(&uevent_handler_list_lock);
    135 
    136     return err;
    137 }
    138